Finishing process and composition

ABSTRACT

A dispersion, suitable for finishing substrates such as wood, metal, leather, paper, fabrics, plastics and the like, having a continuous liquid phase and a dispersed polymer phase which undergoes only partial coalescence on drying under ambient conditions thereby being easy to work (sand). On being subjected to coalescing means substantially complete coalescence can thereafter be obtained.

United States Patent [191 Craven [4 Oct. 16, 1973 FINISHING PROCESS ANDCOMPOSITION [75] Inventor:

[73] Assignee: E. I. du Pont de Nemours and Company, Wilmington, Del.

[22] Filed: June 29, 1971 [21] Appl. No.: 158,092

Related U.S. Application Data [63] Continuation-impart of Ser. No.14,632, Feb. 26,

1970, abandoned.

James M. Craven, Wilmington, Del.

[56] References Cited UNITED STATES PATENTS 2,582,354 l/l952 Powell eta1. 260/32.8

3,549,398 Watson 117/64 R 3,397,166 3/1968 3,450,652 6/1969 3,331,8017/1967 3,647,516 3/1972 3,446,769 5/1969 3,304,279 2/1967 3 ,45 1,9786/1969 3 ,222,208 12/1965 Primary ExaminerWilliam D. Martin AssistantExaminerWilliam R. Trenor Attorney-Robert W. Black 5 7] ABSTRACT Adispersion, suitable for finishing substrates such as wood, metal,leather, paper, fabrics, plastics and the like, having a continuousliquid phase anda dispersed polymer phase which undergoes only partialcoalescence on drying under ambient conditions thereby being easy towork (sand). On being subjected to coalescing means substantiallycomplete coalescence can thereafter be obtained.

6 Claims, No Drawings FINISHING PROCESS AND COMPOSITION I Thisapplication is a continuation-in-part of the copending application Ser.No. 14632, filed Feb. 26, 1970, now abandoned.

This invention relates to a process and composition for finishingfurniture andother articles with a finish comprising one or morepolymeric coating layers.

This invention is a dispersion consisting essentially of a dispersedcontinuous liquid phase comprising an organic liquid free of halogensubstitution and a dispersed phase comprising particles of a linearpolymer which polymer has a Tg between about C. and 70 C. is

amorphous and has at least 50 percent by weight acrylic monomer units,said polymer being soluble in common solvents, said disperse phase beingsubstantially insoluble in said liquid phase at 25 C., said dispersionforming a layer having between -60 percent coalescence when applied anddried by evaporation of volatile components at about C.

Preferably the polymer has a Tg between about 25 C. and 70 C. and mostpreferably between C; and 70 C.

The polymer present in the disperse phase is preferably at least onemember of the group consisting of poly- (alkyl acrylates), poly(alkylmethacrylates), interpolymers of an alkyl acrylate and an alkylmethacrylate, and interpolymers of about -999 percent by weight of unitsof an alkyl acrylate or an alkyl methacrylate and about 01-50 percent byweight of units of another ethylenically unsaturated compound selectedfrom the group consisting of poly(vinyl acetate), polystyrene,

poly(vinyl chloride), poly(vinylidene chloride).

The composition may also contain a pigment.

The polymeric dispersed phase may consist essentially of particleshaving a major cross-sectional dimension of between about 0.01 and 25microns and most preferably the major cross-sectional dimension isbetween about 0.05 and 1 micron.

In one embodiment the continuous liquid phase consists essentially of amixture of an organic liquid which is a non-solvent for the polymer at atemperature below 39 C. and an organic liquid which is a solvent for thepolymer at a temperature below 39 C., at least part of the former havinga slower evaporation rate than at least part of the latter. Preferablythe weight ratio of nonsolvent to solvent is about 50:50 to 99:1.

Typically the liquid comprising the disperse phase is an aliphatichydrocarbon and the weight ratio of polymer to continuous phase isbetween about 20:80 to 70:30, preferably between about 30:70 to 40:60.

This invention also comprises a process of applying to a surface of asubstrate the above dispersion and forming therefrom a layer of thedispersed phase having between about 20 to percent coalescence, rubbingthe layer with an abrasive to modify its smoothness, and subjecting theresulting abraded layer to coalescing means to form a substantiallycompletely coalesced layer.

The coalescing means typically comprising contacting said layer with asolvent and subsequently evaporating said solvent.

The disperse phase is usually made of a polymer having a Tg of at least10 C.; and in some applications a polymer having a Tg of at least 40 C.is preferred. Tg" refers to the glass transition temperature."

The polymers of the claimed range have a Tg between such limits as toeffect a balance between case of coalescence by practical commonly usedmeans (in application) and mar resistance under prolonged heavy load (ofa surface in use). Raising Tg tends to result in increased difficulty incoalescence. Lower Tg tends to decrease resistance to 'flow under heavyload. The Tg range of the polymers in the dispersion of the claimedinventiomresults in satisfactory resistance to flow of a surface in afinished article. Preferred ranges of Tg provide even better useproperties of the polymer in the finished article.

Similarly, the amorphous nature of the polymer helps provide forcoalescence. This property together with solubility of the polymer incommon solvents tends to provide for coalescence by means not harmful tothe substrate to which this finish is applied.

Percent coalescence of a layer is measured by the abrasion resistance ofa layer compared to the abrasion resistance of a completely coalescedlayer of the same material determined as described hereinafter. I

The dispersion of the present invention forms a partially coalescedlayer between about 20 and 60 percent coalescence. It has been founddesirable in some applications to form such a layer, undesirable in thefinal product, because of the ease of working (sanding) such a layer.Further coalescence of this intermediate product provides asubstantially completely coalesced layer.

The partially coalesced layer is suitable for working when the volatilesolvent has evaporated and the presence of the partially coalesced filmcan be ascertained at that time. Because conditions of the industry aresuch that work is accomplished at ambient conditions the dispersion ofthe invention must form a partially coalesced film (layer) at 25 C. andambient environment. Film formation is rather rapid. However, forpurposes of uniformity the conditions of the claimed invention areconsidered met if at 24 hours after application of the dispersion at 25C. and under environmental conditions the layer formed has the requireddegree of coalescence.

Without being bound thereby, it is thought that a coalesced layerformedfrom an organosol is the result of a gradual progression from thedeposition of discrete particles through a stage wherein the particlescontact (with the presence of voids) but retain their particleidentity-to the final stage wherein no particle indentity is observedand voids in the layer are substantially eliminated. The presentinvention provides a dry partially coalesced film or layer on thesurface of a substrate. This dry coalesced layer is readily worked.

DEGREE OF COALESCENCE Degree of coalescence is measured by the abrasionresistance of a given layer of polymer (film) in cycles/- mil (asdescribed hereinafter) as compared to the abrasion resistance of acompletely coalesced film. This method can also be used to formulatedispersions which will yield the desired degree of coalescence onapplication to a substrate. Such a procedure is described in Example 1with the description of the test method.

- For ease of coalescence, polymer should dissolve at room temperaturein at least one of the following common solvents or a mixture thereof.Aromatic hydrocarbon, b.p. C., such as toluene, xylene; C,-C aliphaticor-alicyclic primary, secondary or tertiary alcohol, such as methanol,ethanol, isopropanol, butanol, amyl alcohol, methyl isobutyl carbinol,cyclohexanol,

t-butyl alcohol, 2-ethyl-hexanol; C -C aliphatic or alicyclic ketone,such as acetone, diisobutyl ketone, methyl ethyl ketone, ethyl amylketone, isophorone, methyl isobutyl ketone, methyl isobutyl ketone,diethyl ketone, mesityl oxide, cyclohexanone, diacetone alcohol; estersof C C aliphatic acid with a C -C aliphatic alcohol, such as ethylacetate, isopropyl acetate, methyl acetate, n-butyl acetate, sec-butylacetate, isobutyl acetate, n'propyl acetate, amyl acetate, butyl lactateethyl lactate, isobutyl isobutyrate, a-methyl isoamyl acetate; C -Cpolyether, such as mesityl oxide, 7

butoxyethyl alcohol, butoxyethyl acetate, monobutyl ether of diethyleneglycol, monoethyl ether of diethylene glycol, ethoxyethyl alcohol,ethoxyethyl acetate, monoethyl ether of triethylene glycol,metoxyethanol, monomethyl ether of diethylene glycol.

To test for solubility, mix 0.03 g. of polymer powder 1 ml solvent in atest tube and insert a stopper. Gentle shaking should be sufficient todissolve at least 95 percent of the polymer in less than 24 hours. ifall the polymer dissolves to give a clear or slightly hazy solution, itis considered soluble. If a trace of insoluble powder remainsundissolved, the polymer is still considered soluble. if the polymerremains visible whether swollen, broken up, emulsified or unaffected, itis considered insoluble even though some may have dissolved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The continuous liquid phase maycomprise a. mixture of an organic liquid which is a non-solvent for thepolymer at a temperature below 39 C. hereinafter called non-solvent andan organic liquid which is a solvent for the polymer at a temperaturebelow 39 C. hereinafter called solvent, at least part of the nonsolventhaving a slower evaporation rate than at least part of the solvent. Thisprovides a preferred .means for obtaining a predetermined degree ofpartial coalescence. It is often preferred that about 50-100 percent byweight of solvent have a slower evaporation rate than about 50-100percent by weight of non-solvent. Some of the most useful embodiments ofthe composition employ an aliphatic hydrocarbon as the nonsolvent (e.g.one or more members of the group consisting of naphtha, kerosene,hexane, mineral spirits and the like), with solvent being another kindof volatile organic liquid (eg one or more members of the groupconsisting of aromatic hydrocarbons, ketones, esters, ethers, alkanolsand the like).

If there is any undue increase in viscosity or tackiness of a particularcomposition before or during its application to a substrate, or if thecoating undergoes too much coalescence during drying so that it is notreadily worked this indicates that the polymer component is notsufficiently insoluble in the continuous phase. Example l teaches how toprepare compositions of the present invention from compositions outsidethe scope, They may be brought within the scope by some of thetechniques recited below.

(1) increase the ratio of non-solvent to solvent;

(2) replace some solvent with more volatile solvent;

(3) replace some solvent with a less volatile nonsolvent.

The weight ratio of non-solvent component to solvent component in mostcases is preferably about 50:50 to 99:1; especially preferred is a ratioof about 75:25 to 95:5 of nonsolvent/solvent.

The liquid phase is volatile" in the sense that it can be evaporatedunder conditions which are not harmful to any component of the coatedarticle.

Elevated temperatures are not considered satisfactory for wood for longexposures and therefore coalescence of polymer coatings for wood, onwood are best carried out by a solvent treatment at room temperature orslightly elevated temperature. Polymers such as polyvinyl chloride whichrequire for purposes of this invention excessive heat to coalesce arenot considered suitable.

The dispersion can also comprise a dispersion stabilizer adapted torender the composition resistant to agglomeration and settling. Anynon-volatile components that settle out during prolonged storage of thecomposition (e.g. several months or more) can usually be redispersed bya brief period of agitation. The stabilizer content is usually about1-20 parts, preferably about 4-8 parts, per 100 parts by weight ofpolymer component. One useful stabilizer is the product of reactingpoly( 12- hydroxy stearic acid) with certain acrylic compounds. Thegraft copolymers described by Armour, et al. in the claims of Swiss Pat.No. 464,528, granted Oct. 31, 1968, illustrate another useful type ofdispersion stabilizer. in one embodiment of the present invention theabove described graft copolymer comprises all or part of the polymerdispersed phase.

An especially useful type of polymer to use for component the dispersedphase is an acrylic polymer such as a poly(alkyl acrylate), a poly(alkylmethacrylate), an interpolymer of at least one alkyl acrylate and atleast one alkyl methacrylate, an interpolymer of about 50-99.9 percentby 'weight of units of an alkyl acrylate or an alkyl methacrylate andabout 0.1-50 percent by weight of units of another ethylenicallyunsaturated compound copolymerized therewith, or a blend of two or moresuch polymers. Among the preferred compounds copolymerized therewith areacrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile andvinyl acetate.

Other polymerizable components include vinyl chloride and vinylidenechloride.

Some polymers which would be useful are 60/40 MMA/MA 55/40/5 MMA/MA/DMAM/30 MMA/EA /20 MMA/BA 60/40 MMA/ZEHA 75/25 EMA/MA /10 EMA/EA 50/50MMA/BMA 60/39/1 MMA/MA/MAA wherein MMA Methyl methacrylate MA MethylAcrylate EA Ethyl acrylate EMA Ethyl methacrylate BA= Butyl acrylateZEHA 2-Ethylhexyl acrylate BMA Butyl methacrylate DMAMDimethylaminoethyl methacrylate MAA Methacrylic acid The composition cancontain a dispersed pigment in an amount sufficient to provide thedesired color and other-properties; for example, the weight ratio of thepolymer component to pigment can be within the range of aboutl:99-to,99:l. When the composition is to be i used as acolorcomposition, for example, a base coat,

the polymerzpigment weight ratio is usually about 1:99 to 40:60,preferably about 5:95 to 35:65.

Among the useful pigments are burnt umber, raw umber, VanDyke Brown,burnt sienna, raw sienna, mineral black, lithol red; titanium dioxide,ferrite yellow-orange, zinc oxide, zinc sulfide, lead titanate, antimonyoxide, zirconium oxide, white lead, basic lead silicate, lithopone,carbon black, other iron oxides of various colors, lead chromate andmolybdate orange; also the pigments sometimes referred to as pigmentextenders, for example, calcium carbonate, talc, barytes, diatomaceousearth, asbestine, china clay, silica and fine mica; also various knownnitroso-, nitro-, azoand pyrazolone pigments as well as basic dye-,auxanthine dye-, anthraquinone-, phthalo-, cyanine-, and vat colorpigments.

The composition can contain a small amount of material such as polymerin addition to the polymer comprising the dispersed phase if it does notprevent obtaining the desired coating and coalescing properties. Forexample, the composition can contain one or more of the following: zincstearate and other sanding aids capable of enhancing the abrasiverubbing operation; a dissolved polymer known to be useful as astabilizer in polymer dispersions to prevent or retard agglomeration andsettling of the particles; a drying oil; an oilmodified alkyd or othersynthetic resin; a plasticizer (e.g. a non-volatile liquid) forcomponent (B) or any other polymer present; flatting agents; dyes;fungicides; and drying and curing agents, and the like.

In carrying out the process of this invention, at least one layer of thenovel film-forming composition is applied to at least one surface of asubstrate by any suitable coating method, for example by spraying,brushing, spreading, dipping, rolling or flow-coating. When thecomposition is formulated to form a wiping-type color coat, before theresulting coat is dried, it is wiped with a piece of burlap or othersuitable wiping means until the wiped surface has the desired appearanceand the color coat remaining on the surface is present in the desiredamount and location.

The wet coat of film-forming composition is subjected to drying meansuntil the liquid phase has evaporated and the dispersed phase hasundergone partial coalescence. The partially coalesced layer is dryalthough it is to be understood that there may be present residualmaterial from the liquid phase which does not interfere with sanding anddoes not give the layer a wet feel.

The dried coat is rubbed with an abrasive to modify its smoothness. Thenthe resulting abraded coat is subjected to coalescing means such assolvent which substantially completely coalesces the polymeric layer.

The invention makes it possible to obtain coatings which aresurprisingly easy to sand to the desired smoothness even when thecomposition contains little or no pigment or sanding aid. The dry coatmay be rubbed with abrasives typically used such as sandpaper, steelwool or the abrasive action of a felt buffing wheel containing fineabrasive, a wire buffing wheel, or a stream of abrasive particlessuspended in a liquid or gas. The abrasive rubbing action can resulteither in a very smooth surface, or in a surface having a regulated orpredetermined degree or pattern of roughness, for example as tinygrooves, pits or scratches. Such a roughness pattern is sometimesdesired in producing a finish having an interesting surfaceconfiguration or color contrast.

The operation of completing the coalescence of the abraded coat can bedone by (l) heating the coat at a temperature at which the polymer fullycoalesces, or (2) by bringing a solvent for polymer in contact with thecoat followed by evaporation of the solvent, or (3) by applying to theabraded coat a layer of liquid filmforming composition containing afilm-former and solvent for polymer such as by spraying followed byevaporation of the solvent, or by combinations of these or equivalentmethods. A preferrred embodiment of method 3 comprises using the samepolymer in the abraded coat as in the layer applied thereto.

The novel process and composition are beneficially useful for theapplication of durable and attractive clear and pigmented polymericfinishes on various substrates, for example articles made of bare andpreviously coated wood, metal, leather, paper, fabrics, plastics and thelike. The invention makes it surprisingly easy to obtain single'andmultiple layer finish coats having the desired surface smoothness ortexture along with good toughness, clarity and adhesion. When using theinvention to manufacture unsupported polymeric films and sheets, asubstrate is used which can be removed from the coalesced layer ofcomposition.

The layer of composition can be applied to the substrate in the form ofa base coat, wash coat, sealer coat, top coat or the like, orcombinations of two or more such layers. In a finish containing aplurality of layers, the completion of coalescence can be carried out oneach layer individually, or on two or more of the layers in a singelcoalescing operation. In some applications a single coat can be used inplace of two coats needed in a prior art method; for example after thesandedsmooth partially coalesced coat is fully coalesced, it hassatisfactory appearance and toughness for some products withoutrequiring a top coat over the sanded coat.

In the Examples which follow all parts are by weight unless otherwiseindicated.

EXAMPLE 1 Steel panels (4 inches X 4 inches with a 1/4 inch hole punchedin center) are sprayed with a red, steel primer and dried. The thicknessof the primer on each panel is then measured with an Elcometer(Elcometer Instruments Ltd., Droylsden, Manchester, England. Availablefrom Gardner Laboratory, lnc., Bethesda, Maryland). The primed panelsare then sprayed with the solution or organosol to be tested and driedat the desired temperatures. The organosols were dried at roomtemperature and the solutions at 100 C. The total thickness of primerand experimental material is then measured with the Elcometer and thepreviously determined primer thickness subtracted to give the thicknessof the experimental film.

The panels are then abraded on a Taber Abraser using 8-33 sandpaperstrips adhered to the outside of the two rubber wheels. Fresh sandpaperis used for each sample. Using a 250 g. load, the panels were abradeduntil one half of the abraded area of the experimental film wascompletely abraded away exposing the red primer underneath. The numberof cycles required to'do this was divided by the thickness of theexperimental film to give the abrasion resistance in cycles/- mil.

Results are shown in Table I.

TABLE I 1A 1B 1C 1D 1E Organosol', g 20 I 20 100 100 100 Cellosolveacetate, m1... 210 105 29 3D 20 Toluene, ml 105 liutyl Cellosolve, mlMineral spirits", ml. Solvent', ml...

236 224 118 Thickness (rnils).. 1.1 1. 59 3.60 Cycles 261 304 411Cycles/mil 235 194 114 Average cycles/mil- 235 209 116 Percentcoalescence- I 89 49 '55/40/5 MMA/MA/DMAM (MMA=rnethhl methacrylate;MA=methyl acrylate;

DMAM=dirnethylaminoethyl methacrylate) organosol having 54% solids.

Mineral spirits (B.P. l45-215 C., A.P. 57 (3.). 'Aliphatic hydrocarbonsolvent (B.P. 143168 0., Al. 56 0.).

The solution (1A) was made by diluting the organosol with a cellosolveacetate which gave a clear, viscous solution. Films cast from thissolution were clear, hard and tough. The 235 cycles/mil obtained is thevalue used corresponding to 100 percent coalescence.

The (18) sample contains substantial amounts of toluene, a poor solvent,thus retaining some organosol character. The Taber value of 209cycles/mil or about 89 percent of the value for the 100 percentcoalesced materials substantiates the validity of the assumption.

The (ID) sample is an organosol containing 30 ml cellosolve acetatesolvent. The Taber test showed 206 cycles/mil or 88 percent coalescence.

Samples (1E) and (1C) of this invention were rare pared as follows: thedegree of coalescence was reduced for film prepared from (1E) byreducing the amount of coalescing solvent in (ID) from 30 ml to 20 ml.The Taber test gave 109 cycles/mil or 46 percent coalescence. Thismaterial has good sanding properties.

The degree of coalescence in (1C) was obtained using a mixture ofcoalescing solvent (cellosolve acetate) and slow evaporating non-solvent(butyl cellosolve and mineral spirits). The Taber test gave 1 l6cycles/mil or 49 percent coalescence. This material is easy to sand.

EXAMPLE 2 A polymer dispersion is prepared such that the polyrnercomponent is a 5524015 terpolymer of methyl methacrylate, methylacrylate and dimethylaminoethyl methacrylate, and the formula of thecompleted sealer composition is as shown below in Formula 21.

Formula 2.1

Parts Polymer dispersion 55.15 Mineral spirits B.R. l45-2l5C. 23.29Butyl cellosolve" (2-butoxyethanol) 14.79 Cellosolve" acetate 6.77

In preparing the sealer composition, a 'preblended mixture of the lastthree ingredients is gradually added with stirring to the polymerdispersion. A small amount of zinc stearate can also be added whenfurther improvement in sanding properties is desired in someapplications. The polymer dispersion is prepared by (a) providing a'reaction vessel (b) adding to the vessel tyronitrile is the initiator.

each of the ingredients shown in Formula 2.2 below (the seed stage),'(c)stirring Formula 2.2 for one hour while heating at var-79 C., (d) addingan additional 5.8 parts of the initiator, (e) gradually adding over aperiod of 2.5 hours a preblended mixture of the ingredients shown inFormula 2.3 (the feed stage), the temperature in the vessel being keptat about 78-80 C., (f) adding 9.7 parts of the initiator, and (g)allowing the contents of the vessel to be refluxed and stirred for onehour at about 78-80 C. The dispersion has a solids content of about 45.4percent, and the polymer particles have an average diameter of about 0.1micron. The polymer has a Tg of about 53 C. Azobisisobu- Formula 2.2

Parts by Weight Methyl methacrylate 73 Initiator 3.5

Formula 2.3

Parts by Weight Methyl methacrylate 876 Methyl acrylate 683Dimethylaminoethyl methacrylate Stabilizer 340 The stabilizer used isprepared as follows:

The stabilizer ingredient is a 33 percent solution of a dipersionstabilizer made by a process which comprises first making a precursor byreacting poly( 12- hydroxy stearic acid), molecular weight about 1500,with glycidyl methacrylate; and then copolymerizing the resultingprecursor with methyl methacrylate (MM) and methacrylic acid (MAA), theMMzMAA ratio being 98:2.

More specifically, the stabilizer is prepared by (a) heating a mixtureof 93.97 parts of commercial l2- hydroxy stearic acid, 5.22 parts ofVM+P naphtha, 5.22 parts of mineral spirits, B.R. l452lS C., and 0.37part of catalyst (isopropanol ester of orthotitanic acid) under anatmosphere of nitrogen, while removing resulting poly(IZ-hydroxy stearicacid) solution with 5.90 parts of glycidyl methacrylate, 20.97 partsVM+P naphtha, 20.98 parts of mineral spirits, 0.10 part ofcocodimethylamine made from a mixture containing coconut-oil fatty acids[about 95 percent of the amine being the tertiary amine C I-l N-(CH and0.5 part t-butyl catechol; (c) refluxing the resulting mixture until theacid value is about zero; (d) adding gradually over a period of threehours to a refluxing mixture of 11.74 parts of ethyl acetate and 5.87parts of butyl acetate, a mixture of 32.02 parts of the precursorsolution resulting from step (c), 1601 parts of methyl methacrylate,0.33 part of methacrylic acid and 0.67 part of azodiisobutyronitrile;(e) refluxing the mixture for an additional two hours; and (f) addingenough VM+P naphtha so that the resulting composition contains about 33percent of nonvolatile component.

EXAMPLE 3 A coating composition is prepared in the manner described inExample 2 except the amounts of ingredients used in making the polymerdispersion are such that the polymer component is a 57.5:40:2.5terpolymer of methyl methacrylate, methyl acrylate and dimethylaminoethyl methacrylate.

The resulting coating composition is used in a finishing process whichconsists of (1) providing some wall panels and pieces of furniture madeof various kinds of wood, some of which have been coated with anordinary furniture type wash coat and filler coat, (2) sanding the woodarticles provided in Step 1 with fine sandpaper, (3) spray coating eacharticle with a pigmented wiping stain ofa type commonly used byfurniture manufacturers, (4) wiping the stain coat with a clean cloth toobtain the desired color and grain appearance, (5) drying the staincoat, (6) spray coating each article which was not treated with washcoat and filler with the coating composition described above to a dryfilm thickness of 2.5 mils, (7) drying the coat for 30 minutes at 25 C.,the dried coat being partially coalesced, (8) sanding the partiallycoalesced coat with fine sandpaper until it appears to be perfectlysmooth, (9) completing the coalescence of the sanded coatby exposing itto methylene chloride vapor at 30 C. for one minute, (10) allowing thecoat to dry for 1 hour at 25 C., (11) sanding the coat lightly with No.400 sandpaper and then rubbing it lightly with No. 0000 steel wool, and(12) applying a thin coat of furniture wax. The finish has goodappearance and durability. The partially coalesced coat is sandedcompletely smooth with surprising ease and speed, and the layer ofsubsequently coalesced polymer composition is unexpectedly effective asa combination sealer and top coat.

The claims are:

l. A process which comprises applying to a surface of a substrate adispersion consisting essentially of a continuous liquid phase free ofhalogen substitution and consists essentially of a mixture of an organicliquid which is a non-solvent for the polymer at a temperature below 39C and an organic liquid which is a solvent for the polymer at atemperature below 39 C., at least part of the former having a slowerevaporation rate than at least part of the latter. and a dispersed phasecomprising particles of a linear polymer which polymer has a Tg betweenabout 10 C. and C., is amorphous and has at least 50 percent by weightacrylic monomer units, and is soluble in at least one common solvent at25 C., said disperse phase being substantially insoluble in said liquidphase at 25 C., said dispersion forming a layer having between 20-60percent coalescence when applied and dried by evaporation of volatilecomponents inthe liquid phase at about 25 C., forming therefrom a layerof the dispersed phase, rubbing the layer with an abrasive to modify itssmoothness, and subjecting the resulting abraded layer to coalescingmeans to form a substantially completely coalesced layer.

2. A process according to claim 1 wherein the coalescing means comprisescontacting said layer with a solvent and subsequently evaporating saidsolvent.

3. The process of claim 1 wherein the polymer present in the dispersephase has a Tg between about 40 C. and 70 C. and is at least one memberof the group consisting of poly(alkyl acrylates), poly(alkylmethacrylates), interpolymers of an alkyl acrylate and an alkylmethacrylate, and interpolymers of about 50-999 percent by weight ofunits of an alkyl acrylate or an alkyl methacrylate and about 01-50percent by weight of units of another ethylenically unsaturated compoundselected from the group consisting of poly(vinyl acetate), polystyrene,poly(vinyl chloride), poly(vinylidene chloride).

4. The process of claim 3 wherein the dispersion also contains apigment.

5. A process according to claim 3 wherein the coalescing meanscomprising contacting said layer with a solvent and subsequentlyevaporating said solvent.

6. A process according to claim 4 wherein the coalescing meanscomprising contacting said layer with a solvent and subsequentlyevaporating said solvent.

2. A process according to claim 1 wherein the coalescing means comprisescontacting said layer with a solvent and subsequently evaporating saidsolvent.
 3. The process of claim 1 wherein the polymer present in thedisperse phase has a Tg between about 40* C. and 70* C. and is at leastone member of the group consisting of poly(alkyl acrylates), poly(alkylmethacrylates), interpolymers of an alkyl acrylate and an alkylmethacrylate, and interpolymers of about 50-99.9 percent by weight ofunits of an alkyl acrylate or an alkyl methacrylate and about 0.1-50percent by weight of units of another ethylenically unsaturated compoundselected from the group consisting of poly(vinyl acetate), polystyrene,poLy(vinyl chloride), poly(vinylidene chloride).
 4. The process of claim3 wherein the dispersion also contains a pigment.
 5. A process accordingto claim 3 wherein the coalescing means comprising contacting said layerwith a solvent and subsequently evaporating said solvent.
 6. A processaccording to claim 4 wherein the coalescing means comprising contactingsaid layer with a solvent and subsequently evaporating said solvent.